Much easier way seems to be the idea that was detailed on this forum some time ago of simply cutting two circular pieces out of the bonnet insulation under the jet positions. This uses the heat from the engine at least at the jets. The writer tidied it up using desk cable tidies. I have not tried this in my Fiesta yet but I did it on my son's Mondeo and so far with the last few days sub zero temperatures he thinks it works.
Another idea I saw many years ago was to extend the plastic tubing and make a coil around the top hose, wrapping wide tape around the coil to retain it in place. Again I've not tried this as I think the water would freeze again by the time it reaches the jets. The above method seems a better idea.

For what I assume is a pretty small cost (relatively speaking) I consider this is a major omission on the Fiesta. You get heated rear/front screens and heated mirrors but no heated washer jets! Doesn't matter how strong you mix your screen wash... with exposed washer jets like this.... your ambient -5C (like this morning) is God only knows what with a 50/60+ mph wind hitting the jets!!

A much better design would be to recess the washer jets down by the windscreen wipers. I've had this on other cars and they don't freeze up half as much.

Yeah they freeze up, you need to have the screen on a little while before you get any effect. fitted all the wires and stuff which was pretty simple, just a case of finding various wires and such to get them hooked up. Not today though, busy busy